Modeling and simulation of heat-mass transfer and its application in wood thermal modification

Abstract

Wood is a type of renewable and natural material, with most of its end application related to building materials. However, hygroexpansion and anisotropy in wood markedly shorten its service life and value. In this study, wood thermal modification was used to improve wood quality, and a heat-mass transfer model was established based on practical production process. The software COMSOL Multiphysics was used to solve this coupling transfer model. Relationships between temperature and moisture content, temperatures of the medium under thermal treatment, and treatment time, were established. Results indicated that this coupling model and method can be used to simulate and solve heat-mass transfer during wood thermal treatment, and the simulation results were found to be consistent with the measured results. The temperatures at the wood surface could achieve the target temperature within a considerably short time, whereas that at the wood central point was difficult to obtain. The cross-section of the heat convection boundary obtained the highest temperature and the lowest moisture content, whereas the cross-section of the symmetry boundary obtained the lowest temperature and the highest moisture content. These results can be used to devise a wood thermal treatment schedule, determine the heat and moisture distribution, and control the wood heat treatment process. Consequently, guidance for wood thermal treatment is provided to reduce energy and time consumption.